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Summary Excretory system - Grade 11 Biology
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Summary of the entire excretory system chapter for Biology, including detailed diagrams and definitions.
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Excretory systemExcretion - the removal of waste products from the body (water, CO2, and
nitrogenous waste formed from metabolic reactions.)
Metabolic reactions - all the reactions taking place in the body.
If waste products accumulate may become highly toxic and could damage body
tissue
Water is not toxic, accumulation of water would disrupt homeostasis and cause
complications..
Homeostasis - maintaining the internal environment of the body so that cells can
function properly.
LIVER
- Not an excretory organ but many waste products are formed in the liver and
excreted elsewhere
Nitrogenous waste
- Urea; formed from excess amino acids. Amino acids are broken down into
ammonia (toxic) then into urea, a process called deamination.
- Uric acid; formed from the breakdown of nucleic acids
- Creatine; found in skeletal muscle cells, formed by creatine phosphate
Non-nitrogenous waste
- Toxins and drugs; painkillers, tranquilisers and nicotine
- Alcohol; causes permanent damage to liver cells
Other excretory products in liver
- Bile pigments; formed from breakdown of red blood cells
- Cholesterol; formed from breakdown of bile salts
To maintain homeostasis - important to get rid of waste products which diffuse into
the blood system. Then carried to excretory organs, then removed by excretion
EXCRETORY ORGANS
Kidneys Lungs Skin Colon / Gut
Excrete all of the CO2 which released Water, salts, small Bile pigments and
nitrogenous waste from cellular respiration amounts of urea on cholesterol pass into
carried to lungs through surface to form sweat small intestine and
Excretes blood from sweat glands excreted in the faeces
non-nitrogenous waste,
such as CO2, excess CO2 is exhaled along Water in sweat Mucus and bacteria also
water, ions, hormones with a little bit of water evaporates, heat is lost excreted in feces
and drugs and heat and body cools
Defecation - the
removal of undigested
, food materials
URINARY SYSTEM
The main function - maintain homeostasis by regulating the volume and
concentration of body fluids; done by filtering and reabsorbing materials from blood
Structure of urinary system
The urinary system - found in abdominal cavity
NOTE: The right kidney is lower than the left kidney as pushed down by right lobe of
liver.
In males, the urethra passes through penis and carries urine and semen
In females, it only carries urine which exits through separate opening to vaginal
opening.
Adrenal glands - endocrine glands, sit above kidney, not part of excretory system.
Secrete aldosterone which plays role in salt concentration
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